Ultrasound systems have been widely used in medical fields to obtain information on objects of interest in a target object. Using high-frequency sound waves, an ultrasound system can provide high-resolution images of the target object in real time without requiring an invasive surgical operation on the target object. Due to their non-invasive nature as well as non-destructive nature, ultrasound systems have been widely used in the medical field.
The ultrasound system comprises an ultrasound transducer for generating ultrasound signals and transmitting/receiving them. The ultrasound transducer comprises a piezoelectric layer made of piezoelectric ceramic material such as PZT (Lead Zirconate Titanate), etc. that generates ultrasound signals in response to electrical pulse signals, and transmits the ultrasound signals to a target object, receives echo signals reflected from the target object; transforms the reflected echo signals into electrical signals, and transmits the electrical signals to an ultrasound imaging device. Generally, the piezoelectric ceramic element of the ultrasound transducer is placed between a backing block and an acoustic matching layer.
The backing block is formed by a material having a similar impedance value to an acoustic impedance of the piezoelectric ceramic element and having a high damping coefficient. When the electrical pulse signals are applied to the piezoelectric ceramic element, the backing block allows for generation of short pulses of the ultrasound signals by quickly suppressing vibrations of the piezoelectric ceramic element. Further, the backing block works to decrease heat from the piezoelectric ceramic element, and absorbs the ultrasound signals from a back side of the piezoelectric ceramic element.
The acoustic matching layer is used to reduce energy loss by reflection of the ultrasound signals due to acoustic impedance difference between the piezoelectric ceramic element and the target object. The acoustic matching layer is made of a material having an impedance value corresponding to a value between the acoustic impedance of the piezoelectric ceramic element and the acoustic impedance of the target object.
Generally, since a Flexible Printed Circuit Board (“FPCB”) for signals and a FPCB for ground are necessary to drive the piezoelectric layer, a wiring structure of the ultrasound transducer is complex.